Challenge Questions

Possibly. Hansen and Paige show a fairly good correspondence between temperature and season and there seem to be fairly repeatable frost patterns. The problem might be calibration between the temperature and location - making a graph over several Pluto years should clarify that.

Regards,

Mission Specialist Methuselah

When it gets to below 25°C it is winter for me. For some people 25°C is summer and for some…they have never even experienced 25°C. So taking out a thermometer on Pluto, what temperature would you consider to be summer or winter…?

To imply that there are 'seasons' would assume that Pluto has a rotational axis, which is tilted at X degrees, and could be seperated into hemispheres. Given that these are present, where is an atmosphere in which seasonal changes may occour? And just who would give a pair of foetid dingos kidneys anyway?

"Hey Maude, lets see what the locals are drinking, maybe they'll tell us when's a good time to plant peas".

Based on reading in Wikipedia, it seems that Pluto has an atmosphere when close to the Sun, but none when farther away (the gasses freeze and fall the the surface as ice). When Pluto comes back towards the sun, the gasses sublimate and cool the dwarf planet, reducing its average surface temperature.

Depending on the nature of the thermometer, it may be possible to determine temperature variations in the crust between Pluto's seasons. A much easier way to determine the season on Pluto might be to measure the density or pressure of gas at its surface, for which a thermometer is not appropriate.

Note that this does not consider other ad-hoc circumstances such as an unusually large quantity of nitrogen currently in Pluto's atmosphere which should settle over the next few decades.

Well done!

Codemaster -

To scale the solar power density on the surface of Pluto, wouldn't you have to convert Astronomical Units into meters? Or else express the power density in Watts per square Astronomical Unit?

Hello rocketsurgeon

No, it's only the ratio of distances Sun-Earth and Sun-Pluto that matters. As distance Sun-Earth = 1 AU by definition, ratio of power densities = 50².

Cheers..........Codey

just look for polaris. That's north. Or the southern cross. That's pretty close to south.

It's always football season on Pluto, though, so there's no need for the thermometer.

Polaris North? He he - But can anyone say which way Pluto's North pole does point?

It points north...where else would the north pole be?

I'm no brain sturgeon here, but thats an easy on.

T-Dub

Well, it is very probable that Pluto does not have a magnetic field because it probably doesn't have a molten core. So magnetic north does not exist.

What's left? The next best thing is Pluto's rotational axis, which is 120° off the ecliptic, so neither rotational pole points to Polaris.

I am not sure, but I would guess there is an astronamical convention for which pole is designated which in the absance of a magnetic field, probably it would be the pole that faces closest to the side of the ecliptic that the Earth's north pole points.

anonymous hero raises an interesting issue--wifi on planets and moons and asteroids our spacecraft have visited. What would be the downside of creating solar-powered transceivers that link directly into the internet? They could be provided with wifi so that astronauts could use them as an alternative method of communicating with earth and it would be interesting to be able to connect to phobos's URL and find out the temperature and maybe download a recent picture of the surface of mars directly from the red planet. It would equip NASA with a round the clock observation crew if anything of interest happened on Mars. Thousands might link up to follow a minute-by-minute update on a dust storm. Someone should kick NASA's hind end and get them working on this.

"...if anything of interest happened on Mars."

Do you mean like that small image of Elvis turns up again?

The common temperatures given for the surface of Pluto varies between 40K and 50K, and it is often stated that the temperature appears "uniform" across the planet*. As these are very close to the average temperatures we would expect for the sun-facing side of a planet** at that distance, this temperature seems unlikely to apply also to the dark side of Pluto - which of course we never see from the Earth (note that this is in contradiction to what you will see on most amateur astronomy pages - however, this reference at least appears reasonable).
*How good is the resolution at the peak wavelength of 50-um anyway?
**In addition, we would not expect much tidal heating, as Pluto and Charon are already tidally locked - though there may be residual heat from the interior from when they were not.

The probable temperature change between day and night will mean that we cannot readily distinguish season with a single surface measurement. But we will certainly be able to tell the difference between summer and winter within about 6.4 Earth-days if we also bring a clock. Of course, the large ellipticity of Pluto's orbit means that the daytime temperature varies considerably through the Pluto year; if "good" means that our thermometer is well-enough insulated to act as a radiometer, we could also estimate orbital distance - provided that we are in a region that sees daylight.
We may also be able to distinguish season by measuring the temperature at a depth sufficient to average out a few days of surface variation; if we measure the temperature as we go down, we may even be able to extract an approximate time profile of previous temperatures - which could give us an indication of what part of summer (or winter) we were in.

(P.S. I'm assuming that we lost track of time on the way out there [difficult for a human to get that far out given the length of the Pluto year, but maybe I was cryo-preserved...], also that I don't know where I landed - otherwise I'd know all this before making any measurements)

Quite so. I took the minimalist approach when reading the challenge. If you have access to other equipment, then you need a much shorter time. And, digging into the substrate would be a really good approach!

I guess that we need to define that is meant by season. My first inclination would be we are talking about spring, summer, fall, or winter. But even on earth, we have different meanings for the word season. Some groups of people in Australia and India have six or eight seasons per year depending on what is happening in the environment around them. For some people in the USA their lives revolve around baseball season, football season, basketball season, etc.

Even if we use the standard spring/summer/fall/winter definition, what does that mean on Pluto? We have seasons on earth because the rotational axis of the planet is inclined. Pluto has a very eccentric orbit so its changes in temperature are more dependent on how far it is from the sun. I don't see how a thermometer would help much - except the challenge question says you are approximately 50 AU's from the sun. That is as far from the sun as Pluto gets. It must be coldest then. It must be the dead of winter and your thermometer would tell you so if you knew the relationship between temperature and position in it orbit.

Thanks,

Jim

Regarding Pluto's distance from the sun, I didn't quite read it that way - to my understanding (?) the distance given could equally be where-ever I was on the way (don't ask me why I was taking a long way around). Then of course the use of the present tense would indicate that Pluto is about 32 A.U. from the sun. I am inclined to ignore both implications.

Then to seasons - the complicating factors for on Pluto's insolation are more significant than for the Earth, because of the larger inclination of the polar axis. This is easiest to see if we choose conditions at the equator.
You already considered the effect of distance from the sun, but the variation in the angle that the light strikes the equator is actually more significant. Twice a year year when other parts of Pluto have Equinoxes, the sun will be directly overhead at mid-day, so around mid-day it will be quite hot (except for the short times when the surface is shaded by Charon). When other parts of Pluto have solstices, the equatorial sun will only be 32-degrees above the horizon even at midday - which will reduce the 1-day average insolation by a factor of about 2. I've not so far found find reliablee data on the relationship between the orbital axes and the polar axis, but memory suggests that the equinoxes occur near to aphelion and perihelion. That would make the peak equatorial temperature appreciably cooler during the solstices than at aphelion - and (ignoring changes in surface reflectivity) temperatures at perihelion should be about 1.3 x of those at aphelion.
So we have very significant seasons even at the equator - perhaps we might describe this as two winter peaks per year, plus one cool summer and one hot summer (these terms being relative to impossibly cold, of course). (At the moment, I think the equator is experiencing late summer)
Of course, things are much more straightforward in the non-tropical regions - where the behaviour will be somewhat more similar to Earth's - but one of the poles should have a much hotter summer than the other.
BTW, I rather like the idea that about 96% of Pluto's Arctic area is tropical...

Any real trajectory that would intercept the planet Pluto would be one that would overtake the planet's orbit so that you can minimize fuel required to intercept and land on the planet.

So, I would tend to agree that the planet was near or more precisely, past its orbital apex.

Maybe the intent of the puzzle was to destinate just before the transition through maximum perihelion.

Since the planet's axis is tilted at almost 120° from the ecliptic it probably would be easier (and more accurate) to measure the angle of the Sun relative to the gravitational center of the planet.

The albedo of Pluto's hemispheres is not consistent at all, so any small amount of solar absorption can be confounded by exactly what part of the planet is facing the Sun.

If we assume (as I think you are suggesting) that the present tense means what it says, we are only about 20 years after Pluto's equinox (that's equivalent to a month after equinox on on Earth). As we already know the effective time of year and no part of Pluto is yet in continuous shadow, we could use thermal day-length to approximately determine our latitude. (So we should know the answer within a few days of landing). This situation will continue for a few years yet.

Alternatively, as I think you were proposing(?), we might use the thermometer to cast a shadow and use the shadow's trajectory

There should be no issue judging the difference between spring and autumn, but both methods are liable to errors in the finer detail unless you compensate for the non-spherical equipotential surface of the Pluto-Charon pair. Even with better information than we currently have available that could be tricky unless you can see Charon from where you landed.

As I originally understood Pluto, the 'seasons' there are simply determined by the planet's distance from the sun - 'winter' at aphelion and 'summer' at perihelion.

If the spacecraft in question lands around the 50 AU distance mark (as implied, but not stated), it will be winter and the thermometer (plus a Pluto temperature chart) should easily confirm that over a single day.

If the landing was at some random time, the problem becomes too complex to solve with a thermometer alone. There is apparently some 'global warming' at present, meaning that as Pluto recedes from the sun, it actually gets warmer at present, probably caused by a higher atmospheric pressure. As some of the gases freeze out, this trend should eventually reverse, but I do not think there are presently enough data to say so.

-J

Hi Jorrie

Are you implying that "summer" and winter" on Pluto should be ascribed to the average temperature of the planet rather than the average temperature where you happen to land? I would find that very strange. (You might find it even stranger if you were to land on the dark side of Pluto at an equinox - as the temperature there will be below 10-K).
However, even if we were to accept planetary-average-temperature as the definition, we would need to check the numbers carefully, as the combination of uneven heating and the 4th power radiation law might still result in average temperatures being lower during the solstices than they are at aphelion. (Note that is a very different thing from the average temperatures as observed from the Earth - these could well be higher near the Equinoxes than they are at present, because the side we see will face the sun almost continuously)

Then there is the use of the term "global warming" to describe what is simply a phase lag that is similar to what we experience every summer. Are you sure you want to propagate this - given the misuse various global-warming "sceptics" have made of this sort of effect?
("Sceptics" is in quotes because a true sceptic (= one who reflects on matters) does at least check the basis of his objections.

I believe the warming and cooling has something to do with the trace atmosphere changing state from gas to precipitation. The energy released and absorbed during that transition warms or cools the planets surface temperature.

Additionally, Pluto's atmospheric temperature (when it has an atmosphere) is inverted. That is, the higher the altitude the warmer it gets. I don't remember at what rate that happens, but I do remember reading something about that.

So, Jorrie is probably right in that the surface temperature does not directly reflect the physical orbital position. It is not a simple correlation.

Also, since it takes nearly 248 years for a complete orbit, changes happen slowly.

Hi Fyz, you asked: "Are you implying that "summer" and winter" on Pluto should be ascribed to the average temperature of the planet rather than the average temperature where you happen to land?"

In fact, yes, if I take my cue from astronomers who say that the side of Pluto that we can observe is now slowly going "into a frosty winter", due to the larger distance from the sun. Read with that the fact we always observe the 'summer hemisphere' of Pluto, as we define it for Earth. So it is getting winter in the 'summer hemisphere', so to speak. A little confusing, to say the least.

"(You might find it even stranger if you were to land on the dark side of Pluto at an equinox - as the temperature there will be below 10-K)." I don't comprehend - at an equinox, don't all parts of Pluto see the Sun every 6 hours, or so? If true, there should be very little difference in day/night temperatures. It may be different during the 'midnight sun', where the other pole has a 'midday-night'. However, the occultation measurements, showing the temperature inversion in the atmosphere, do not seem to support a big difference in polar vs. equatorial temperatures.

Nevertheless, I still believe that if the spacefarers know where on Pluto they have landed, they know the Pluto temperature map and they observe the sun (or lack of sun) for a few days, they could determine the season by means of an accurate thermometer.

"Then there is the use of the term "global warming" to describe what is simply a phase lag that is similar to what we experience every summer."

I've first read this term in 2002 in a MIT news office article about a press release by Williams College, University of Hawaii, Lowell Observatory and Cornell University, led by James Elliot, professor of planetary astronomy at MIT. I then got the impression that the cause is not well understood: "This is a very complex process, and we just don't know what is causing these effects on Pluto's surface", Elliot said. "That's why you need to send a mission."

It may be a bad term to use, yes, but that's apparently what the press release said.

-J

Hi Jorrie
Whoops - I meant solstice when I typed equinox. Which (position-wise) corresponds approximately to Pluto being at an end of the minor axis of the orbital ellipse. Based on the inverse square law and constant exposure to sun, the hottest region should be hotter at this time of year than at Aphelion - and the cold region colder. On the other hand (as theorised in #8) the uniform temperature at the equator will be relatively low around the solstices, because the sun is only 23-degrees above the horizon.
I believe that the Pluto day is just over 6-days, not six hours. However, at a distance of 40AU the radiation time constant could increase by about a factor of 1600, so even with reduced specific heat and reduced surface conduction I now realise the temperature change during the course of a day temperature could be quite small - which is a bit of a teaser, as I think that would give an expected temperature of about 35K.

I don't see a direct quote of "global warming" - but even if that was said, even the best make verbal drops-off - and not only when being interviewed. Whatever the origin, I prefer not to see such emotive verbal misapplications prompaulgated. Returning to the time delays, the 1600 factor previously mentioned would (other things being equal) scale the Earth's 1-month delay (solstice-to-maximum temperature) to about 130 years on Pluto. Under some conditions we might also expect increase of atmosphere to reduce thermal radiation, to say nothing of surface changes. It is also unrealistic to call the average temperature of the part of Pluto that we can see the "average temperature" of the mini-planet, as the growing cold area that is never exposed to our view only forms a part of the distortion of our "average" measured temperatures. Of course I'm agreeing strongly with the pundits on at least one point - there is a great deal we don't know about little Pluto, and the mission currently on its way will hopefully answer a few of our questions (but doubtless raise even more)

Rgds
Fyz

Hi Fyz

I'm OK with what you wrote, except this: "Returning to the time delays, the 1600 factor previously mentioned would (other things being equal) scale the Earth's 1-month delay (solstice-to-maximum temperature) to about 130 years on Pluto."

My problem is: the part of Pluto that we observe (and can take the temperature of) always has the sun very nearly at zenith. It is a bit like measuring the average temperature at noon, but at a latitude always directly under the sun. If Pluto had no atmosphere, then as soon as it passes solstice, the amount of absorbed sunlight on the observable part decreases for two reasons: (i) increased distance from sun and (ii) some observed parts turn towards the dark side each day.

On the other hand, radiation losses will only drop when the temperature drops, so the average temperature should go down immediately. There may be some heat stored in the soil that causes a delay, but the temperature should not increase due to that, but rather decrease more slowly. So Pluto may have some other mechanism that drives this anomalous increase in average temperature (at least on the observable side). Atmospherics are probably the best buy.

This obviously does not solve the "which season is it" problem of the spacefarers.

-J

"Pluto has always been my favorite planet..."

And my favorite dog.

Thanks. Your comments directed me to the times of the regular eclipses, which are reported to have been regular occurrences from 1985 to 1990. That meant I could correct my comment to AnonHero!

"decades every thousand years or so when every sixth day Pluto experiences a solar eclipse"

That's very interesting - can you provide a reference? (Without that information, and given the locked orbits and how close Charon is to its moon, I'd have expected that there would be regular eclipses at each Solstice - though I doubt that would go on for a whole decade most times).

Actually, since they are tidally locked to each other, the eclipse period should occur every half orbit, or roughly every 124 years. The most recent eclipse period was when it was at its perihelion position, so the next set should occur as it nears aphelion, perhaps starting in the year 2105. Due to its slower orbital velocity near aphelion, the eclipse period should last a bit longer and there should be many more eclipses.

And just 'by the way' the meaning of 'equinox' is equal night (and day), so the eclipses would have occurred when Pluto's equatorial plane was approximately lined-up with the sun, i.e., at an equinox.

http://www.solarviews.com/eng/pluto.htm

Too right - I've been suffering from trypist's word-swap...
(What you write is a nice expansion of what I'd intended)

It seems a bit of a coincidence that the equinox+eclipses are virtually coincident with perihelion/aphelion. Do you know if it might be more than that? (Could the collision that set the present rotation have also created the elipticity?)

BTW, might it be clearer to write lower "angular velocity"?

Fyz

Re: the coincidence of the peri/aphelion positions and the equinoxes -- good question. I don't know. It seems likely that the same 'event' that created this dwarf planetary system was responsible for all of its peculiarties. Might be a decent problem for a dissertation by a celestial mechanic. I once knew a guy who was working on the problem of Uranus' tilt, but don't know if he ever solved it.

With regards to Kepler's Laws, yeah, angular velocity is probably the better term.

Regards.

Thanks

If your associate did resolve the cause of Uranus's tilt*, he didn't get much publicity for his answer...

*For any wits - the joke's a bit passé

I'm very sorry it took me so long to respond....I've been busy....way too busy.

I didn't have a source in my original post, I just surmised that there would be a short time (decades) where regular eclipses occurred followed by long periods where there weren't any. I guessed this knowing the odd out of plane orbit of Pluto and the unusual fact that it spins, and Charon orbits it, on it's side (so to speak). Your request prompted me to look into it and I found something specific:

http://adsabs.harvard.edu/full/1985IAPPP..22...23T

It says that there is an "eclipse season" that lasts about 6 years followed by a period of 120 years till the next. Not bad, obviously I overestimated the amount of time the eclipse season would last (not a few decades), but for an off the cuff guess, I'm feeling good. Also, one clarification, I wasn't suggesting in my original post that the eclipse lasts decades, that doesn't make any sense, I just noticed that when Pluto was in the solar system plane that Charon would be set up to block the sun for a while.

My original point still interests me. I want to know how much of an effect this has on the temperature of Pluto. I have to imagine that losing several hours (up to 6 hours) of sunlight every three days for 6 years has to have a sizable effect.

Counter intuitively, I wonder if Pluto is coldest at that time, the time when it is closest to the sun. Probably not, but still it's an interesting question. It would be interesting to calculate the difference in the incident radiation on Pluto's surface over the course of a day when it's at aphelion and when it's in eclipse season.

My problem was that the only reason I could find for a cycle that was longer than a Pluto year would be precession of the angle of Charon's orbit. Given the small size of Pluto's other moons, I couldn't see a mechanism that would cause a cycle with a period close to four Pluto-years.

Reading on:
Eclipses of the sun by Charon (as seen from Pluto) are only every 6.4 days. The 3.2 day period includes eclipses of the sun by Pluto (as seen from Charon).
If the obscuration of the sun by Charon is at midday, its duration will not exceed 2-hours. This is relatively short compared with thermal time-constants, though I expect there will be appreciable cooling of the immediate surface.
You can approximately calculate the overall effect on Pluto's insolation during the middle of the eclipse season quite easily: based on the duration of an eclipse on Charon, Charon's shadow will scan across Pluto's surface in about 5-hours. The shadow will occupy about 1/3.6 of Pluto's illuminated area. So the proportion of light that is obscured (averaged over a day) will be about (5/(6.4*24))/3.6, or 0.9%. So not very significant overall.

Fyz,

Yeah, you're math looks right. I realize just how elliptical Pluto's orbit is with an Aphelion of 49.3 AU and a Perihelion of 29.6 AU. With incident solar power dropping by r².....roughly 60-65% less light at Aphelion than at Perihelion.

Seeing that Pluto gets 1/3 the light at Aphelion as it does at Perihelion really shows how little a 1% change do to eclipse season is.

The effect would be at least double on Charon.

Roger

Hi Roger.

I'll give some more infos:

As others have already said there is a small atmosphere around Pluto when it is closer to the sun (perihelion) and no atmosphere when it is far away from the sun (aphelion)... Another interesting thing is that -when the atmosphere is present- some gases from the atmosphere escape to the space due to the very small gravity of the planet... The remained gases -of course- are freezing and come on to the surface (so the atmosphere, finally, disappears at the aphelion)... So, in every circle around the sun, Pluto loses an amount of gases... Hence, it loses some of its mass...

Also, Pluto and Charon are likely considered as a "twin planet system" rather than "a planet and its moon"... And this because the size of Charon is very big compared with Pluto (almost half the size of Pluto)...

I was, also, disappointed with the Pluto's demotion and its characterization as a "dwarf planet"... But, unfortunately, he is too small to be considered as a "planet"... There are, also, other objects in the solar system of similar size (or even bigger)... So, if we'd like to consider Pluto as a "planet" then we should consider these objects as "planets" too... And this isn't right...

A planet orbits around the Sun ( the central Star) - an Object ( may be as big as it will be) orbiting a planet can not be a planet; it is and ever will be a moon!

A dwarf or small planet is still a planet!

You Wrote:"So, if we'd like to consider Pluto as a "planet" then we should consider these objects as "planets" too... And this isn't right..."

No actually we don't. We can just say "for historical reasons Pluto is considered a planet" and that's that. This make believe precision we are introducing here by demoting Pluto is a joke. If Titan is a moon, not part of a dual planet system, yet it's bigger than Mercury, things aren't a clear cut now as they are pretending with this new definition.

The point is Science grandfathers in things all the time. Here is a giant example:

By historical convention, a positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current. The motion of negatively-charged electrons around an electric circuit, one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of the electrons.

You see, Ben Franklin and others at the time thought that electricity was due to the flow of positive charges. When they figured out that it was electrons, negatively charged, that were moving around, they said "screw it, it's convention" and that solved that.

There are many other examples in science of this, the point is, some self important committee decided that their muddle definition was better than the existing 70 year old definition and changed it.

and the asteroids are a multi-planet system?

(I hope that you are joking... ...)

When we say "dual planet system" we mean that two planets rotate around each other but they have somewhat similar sizes so their gravity centre (their common point of rotation) is located outside these two planets (i.e. somewhere in the space between them).

The axis of pluto is nearly in the ecliptic of his solar path - so their should be big seasons - this seasons should be measurable by temperaqture!

Because the distance of pluto to the sun is very large there's only a small effect of the solar heating to these seasons - so there is a very good thermometer requiered!

The different distance of pluto on his path around the sun takes greater effect than the position of the axis of pluto - so the seasonal temperature changes shouldn't be measurable (mathmatics required?).

additional:

But the seasons and the Position of Pluto on his Path around the sun corresponds - so: the measurement of the seasonal changes is not possible by temperauture, but the seasonal changes corresponds with the temperaqture effect (~ 1/(r*r)) of the solar distance.

Without knowing the posiion of the axis in the nearest and farest point of the path there's no detailed answer possible.

So it's only a logical question; if the temperature has a defined value there are only two possible positions on the path - each position corresponds to a season.

Your plan is to land on Pluto, our demoted dwarf planet... If you have a plan to land on Pluto, you will have surely planned your trajectory rather carefully, therefore you will know exactly where Pluto is in its orbit before you ever leave the ground. In other words, you know, or should know, already, what season it will be when you arrive.

"You" however have brought "a good thermometer" for the purpose. to determine the season (which you should already know).

Guest states that there is an atmosphere at perigee. This could be said to delimit the Pluto summer season. If the temperature at which the atmosphere forms/collapses is known, then the thermometer can tell you what the season is (provided the thermometer can distinguish between cold as hell and colder than hell). Would it be the freezing point of methane, that marks the change of season?

Maybe, in decades of solar eclipse every 6 days as described by Roger Pink, the cooling effect would be enough to prevent the seasonal formation of an atmosphere. It's semantics then, if we have a perigee without an atmosphere, do we still have "summer" on Pluto?

Last point, in case it is a trick question about brain damage caused by cosmic rays.. Can you determine the season? Can you remember why you brought a thermometer instead of a light saber?

please state how long the stay on the planetelle will last.

When Pluto is closer to the sun (perihelion) ice from its surphase evaporates producing a occasional atmosphere (as others have already said). This produces an "antigreenhouse effect": This evaporation makes the temperature of the surface to further drop (see the Wikipedia about this effect on the Pluto's surface). Then the temperature of its surface is about 43°K. I think that this is the way to find out if Pluto is close to the sun. I suppose that if Pluto is far away from the sun (aphelion) the temperature will be higher than 43°K.

Highly improbable - if the atmosphere is due to the temperature, it needs to remain warmer if it is to persist. That suggests that the most it can do is moderate the temperature changes (and increase any thermal lag).

"... if the atmosphere is due to the temperature, it needs to remain warmer if it is to persist..." ... True, concerning the atmosphere... But the surface itself is supposed to be cooler due to the evaporation... So, I meant to measure the temperature of the surface...

Surely the same should apply? Wouldn't lower vapour pressure combined with lower heat input result in a lower surface temperature. Given that Pluto was only discovered in 1930 and that detailed observation has only really been possible for about 40 years (surrounding the perihelion), I suspect a combination of loose descriptions of modeling, Chinese whispers and conclusion jumping (on the other hand, I could myself be guilty of at least the latter). It is also possible that the observable surface would have been cooling down between solstice and perihelion, because most of what we can see does not see any night around Pluto's solstice; if that is the cause, it would certainly not apply at aphelion.

Fancy going all that way, and only bringing a thermometer. D'oh!

Agreed!

You should at least have a twelve year old scotch or at minimum beer.

but really now what is the next number

1,2,6,42,1806,____

C-YA

Take a new bottle when you leave. It will be about 12 years old when you get there.

1,2,6,42,1806,____

3263442

You should at least have a twelve year old scotch or at minimum beer.

but really now what is the next number

1,2,6,42,1806,____

3,263,442

10649956850806

How much of these numbers do you need?

These numbers are a good example for a snow-ball-effect!

not for 1 and 2, but for all othre numbers:

number = n*n*n*n+2*n*n*n+2*n*n+n, if n=1 the result is 6, if n=2 the result is 42 and so on!

One method would be to determine the atmospheric composition. Both ethane and methane freeze at about the same temperature, but ethane boils at - 88 C, while methane boils at - 162 C. Determine the relative amounts of each in the atmosphere. Is Pluto inside the orbit of Neptune at your arrival time? Pluto's orbit varies from ~ 30 to as far away from the sun as 49 AU. That's another clue.

Firstly, if you are planning to land on Pluto, you must know it's exact position.You must also know it's rotational position and axis orientation.Sasons are determined by the aforegoing information and a thermometer is redundant.

In addition, if you determine it is summer on Pluto, you must be wary of ticks and fleas.While you are at it you may wish to check out nearby Daisey and Goofy as well.

Be aware that some previous visitors have reported being trust off immediately after landing by something resembling a giant claw..but you know how tourists exaggerate.

Good luck in your journeys, and say hello to Walt for me.

Hi,

post 5 by Physicist gave the first step to a solution:

make a hole and measure the temperature down the hole at some depths.

Some meters down the soil remembers the higher temperature of last summer or the lower temperature of last winter.

So if near surface temperature is higher/lower than deeper down then you are approaching summer/winter.

If you tune your thermometer to sufficient resolution you will see at going down the annual cycling temperature translated to oscillating temperature with depth with amplitude of oscillation going down. From this you can estimate the depth per year that the temperature is creeping into the material and the phase of this function at the surface. Max = summer, next zero = fall, Min = winter, next zero = springtime.

RHABE

Yes, perhaps in principle. But even if the only mechanism is thermal diffusion it will need to be pretty sensitive to see very far back - memory suggests that the attenuation is something like a factor of 60 for each cycle. After reading about the complexities of the atmosphere, I now realise that factors such as evaporation and gaseous diffusion could complicate things appreciably - but I still think we should be able to see a gradient near the surface (once we are through the first couple of six-day cycles).

Probably you will be dead before complete your work, I mean, it takes aprox. 260 terrestrian year to Pluto complete only 1 year. So, if there are 4 seasons in Pluto you have to wait 65 years to see what happend! Furthermore you have to travel and it must takes several years to arrive there.

Best regards...

Earth's seasons are determined by the tilt of it's axis and distance from the sun.Likewise for Pluto.Earth's seasons can be determined merely by it's precise orbital position and tilt of it' axis.As mentioned previously, knowing these factors alone is sufficient to determine the season.

To intercept and approach for a landing requires that these facotors be known aforehand.

Why make the obvious overly complicated?

Regardless of the previous considerations, there will be no one season on all of Pluto. It would depend on whether you land on the cold or colder side. Just as on earth, there is no one season (e.g., summer in Australia, winter in Greenland). If there is no axial tilt, there won't be seasons at all, unless Pluto's solar day matches its year. In that case, the far side from the sun would be in perpetual winter and the near in summer, though that would not exactly be seasons as usually understood.

Eugene R. Walker

Yes that's the thing!

There are four seasons

1.) the northpole shows away from the sun

2.) the northpole shows the direction of the move on the path around the sun

3.) the northpole shows straight to the sun

4.) the northpole shows backward to the move on the path around the sun

this means:

1.) the north side is cold - the south side is hot (no day-night)

2.) there are day and night on pluto

3.) the north side is hot - the south side is cold (no day-night)

4.) there are day and night on pluto - just backward to 2.)

Any other question?

I think what we really need to do would be to send most of of government officials and lawyers to check it out. The results of that experiment would benefit all of us. One of the first benefit is it would take years for them to get there and think of the discussion!

and while travelling to pluto the people on Board could play Official Micado - first move looses!

Since Pluto is, at the present time, and for many years to come, inside the orbit of Neptune, you won't be landing on Pluto at all. Perhaps on Sedna.

Steve Pulliam

I would have Micky Mouse use a rectal thermometer. If Pluto's temperature is over 1 degree above normal, it's mating season.

Please spell "atheist" properly, not as "athiest." I like the aphorism, though!

The season will be determined by where on the planet surface you land and when you land there. The thermometer would be of little use.

Will my GPS work there?

what if Pluto is not in an eliptical orbit? have we observed it long enough to say for sure? or is it spiraling away from the centre of the solar system? in which case there wont be any cyclic seasons. but the short answer to the original question is simply "no"